Cardin, D-Md., introduced a bill this week to directly prohibit airlines from charging extra fees for carry-on bags, and he stood by Wednesday as Sen. Chuck Schumer, D-N.Y., unveiled an alternative method of accomplishing the same goal.

Cardin said that passengers should be able to expect to carry baggage on a plane just like they expect a seat, some air to breathe and a restroom.

"Charging for bags that are not checked into the hold is just wrong," Cardin said. "It's outrageous and we need to put an end to it before it becomes a practice in the industry."

The two bills were introduced after Spirit Airlines, a low-cost carrier based in Florida, announced last week that it plans to start charging up to $45 for carry-on baggage that fit only in overhead bins.

The airline unveiled the new fees as part of an "unbundling" strategy that separates specific services from the standard price of a ticket, a move they say will lower prices by an average of $40 each way.

The company describes itself on its Web site as an "ultra-low-cost carrier" that "liberates customers from being forced into paying for services they do not desire or use."

At a news conference Wednesday, Schumer and Cardin said they both want to protect passengers from excessive fees, they just have two different ways of doing it.

Instead of a direct ban, Schumer's bill closes a so-called tax loophole by deeming carry-on luggage a travel necessity, not an extra service.

A Treasury Department ruling issued in January did just the opposite, saying that carry-on baggage is a non-essential item and therefore not subject to the 7.5 percent tax on every dollar collected from airline fares. A statement from Schumer's office said that—under the current tax setup—airlines are encouraged to "bilk consumers" by creating extra fees rather than increasing regular prices.

"Spirit is all about giving customers options to choose what they want to pay for, without subsidizing the choices of others," Baldanza wrote. "Telling Spirit we shouldn't give customers options is like telling McDonald's that they can't sell just a burger and that all customers must buy fries and a soft drink, too. Not everyone wants fries; why should everyone have to pay for them?"

Baldanza said that the fee system would benefit customers by providing lower prices, faster security lines and an easier boarding process.

Sen. Amy Klobuchar, D-Minn., disagreed, saying that the sprinkling in of extra fees makes it harder for customers to figure out the true cost of a flight.

Sen. Robert Menendez, D-N.J., said people are increasingly being "nickel-and-dimed" for things that used to be considered essential.

"The way it's going, the airlines are expecting that you can visit a loved one for a week with a toothbrush and a comb," said Menendez. "And the way it's going, your seat recline will be coin-operated."

Schumer said he spoke to Treasury Secretary Tim Geithner Tuesday to ask if Geithner would ban the practice on his own by overturning the ruling that exempted carry-on fees from being taxed.

"I told him we'd be introducing legislation in case he decided not to," said Schumer. "But if it's an incentive to get him to do it, great, because I told him it's going to pass."

Misty Pinson, a Spirit spokeswoman, didn't rule out keeping the fees in place even if they lose their tax-exempt status.

"This is about offering customers choices," said Pinson. "And Spirit would continue to offer customers options regardless of the tax issue."

Schumer said that whether it's his bill or Cardin's bill that ultimately reins in carry-on fees, it's important to get it done soon to keep the practice from spreading through the entire airline industry.